1. FIELD OF INVENTION
This invention relates generally to devices for distributing granular materials and more particularly to hand operated spreaders for applying fertilizer, grass seed and other like materials on residential lawns.
2. Prior Art
Hand operated devices for distributing granular materials on residential lawns are well known and have been in use for many years. Such devices are available in two general categories, a broadcasting type and a drop type.
U.S. Pat. No. 4,106,704 sets forth a typical broadcast spreader wherein a supply of granular fertilizer material may be placed in a plastic hopper. As the spreader is pushed forward, rotation of the spreader wheels is transferred to an upright shaft which in turn rotates an agitator in the hopper and an impeller positioned below a feed opening in the hopper bottom. Agitator rotation enchances a flow of fertilizer through the opening and onto the impeller where the fertilizer is centrifugally broadcast over a wide area of lawn.
Typical drop-type spreaders are disclosed in U.S. Pat. Nos. 2,678,145, 2,840,275, 3,152,732 and 4,180,184, for example. The '145 spreader has a series of spaced feeder openings formed in a bottom of a hopper bin of the spreader. Flow of material through these openings is regulated by a shutter plate having a like set of openings. The plate may be moved to produce opening alignment or misalignment. Movement of the shutter plate is controlled by rotation of a handle bar of the spreader. This bar connects with the shutter plate through a control rod and pivoted bell crank. The amount of handle rotation and thus rod and shutter plate movement is limited by selective positioning of a calibration plate. The calibration plate in turn interacts with a plate lever attached to the handle bar.
The spreader of the '275 reference is similar in many respects to the '145 spreader. One important difference is the incorporation of over-center locking action to maintain the shutter plate in an open or closed position. The spreader of the '732 reference is also similar but has wheels formed with a series of peripheral lugs to improve wheel-ground traction.
The '184 spreader includes an operating lever pivotally attached to a handle of the spreader. During use one hand of the operator squeezes the lever and handle together. This lever movement is transferred to a control wire connected to a bell crank pivotally attached to a hopper of the spreader. Rotation of the bell crank slides a gate to allow fertilizer in the hopper to flow through aligned slots in the hopper and gate respectively to the ground below. When the lever is released, a spring returns the gate to a position where the slots misalign and flow is stopped.